Radio Frequency Identification (RFID) tags are devices that allow tracking of items to which they are attached. RFID tags may be monitored wirelessly by devices using radio frequency signals, and the RFID tags are typically interrogated by a radio frequency device using a frequency that is compatible with that individual RFID tag. One common device used to interrogate and read RFID tags are RFID readers. RFID readers gather information from RFID tags by transmitting interrogation and command signals within a read zone. These interrogation and command signals cause the RFID tags to respond with desired information. The RFID tags are either passive or active. Active RFID tags have their own power source. Passive RFID tags derive power from signals that originate from external sources. For example, an RFID reader sends an interrogation signal to a passive RFID tag, which the passive RFID tag uses to return data to the RFID reader. More particularly, the interrogation signal is sent on a time varying radio frequency wave that can be used by the passive RFID tag to generate sufficient power for that RFID tag to operate. Moreover, RFID readers can be fixed or mobile depending on the system in which they are being used.
There are currently numerous types of RFID tags. Certain types of RFID tags have control mechanisms contained within the tags. One of the various types of RFID tags that is currently marketed, referred to herein as Electronic Product Code (EPC) Generation (Gen) 2 RFID tags, provides mechanisms that may be set to provide control and functionality for the RFID tags. As used herein EPC Gen 2™ RFID tags refer to RFID tags that operate in compliance with one or more aspects of the EPC Gen 2 Class 1 Ultra High Frequency (UHF) standard published as amendment 18000-6C (originally in 2006 but including any subsequent revisions) to the International Standards Organization 18000-6 standard RFID interface for item management using devices operating in the 860-960 MHz Industrial, Scientific, and Medical band.
Numerous configurations for RFID readers are used to read the RFID tags. In some circumstances, the RFID readers receive power from a hardwired source. In other circumstances, the RFID readers employ batteries. The power level for reading used by RFID readers is typically presented in terms of decibels (dB). RFID readers need to establish communications with the RFID tags that they intend to read. Therefore, RFID readers that employ batteries require sufficient power to the signals supplied to their antennas to cause or enable responses from RFID tags. Thus, for those types of RFID readers that employ batteries, the battery life of the RFID reader is an important issue.
Accordingly, there is a need for a method and apparatus for reading RFID tags using the lowest power consumption.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of various embodiments. In addition, the description and drawings do not necessarily require the order illustrated. It will be further appreciated that certain actions and/or steps may be described or depicted in a particular order of occurrence while those skilled in the art will understand that such specificity with respect to sequence is not actually required.
Apparatus and method components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the various embodiments so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein. Thus, it will be appreciated that for simplicity and clarity of illustration, common and well-understood elements that are useful or necessary in a commercially feasible embodiment may not be depicted in order to facilitate a less obstructed view of these various embodiments.